Cloud computing refers to the delivery of scalable and pooled computing, storage and networking capability and capacity as a service to a network of end-recipients. The name comes from the use of clouds as an abstraction for the complex infrastructure of networks and associated hardware operative within the cloud. Cloud computing provides services for a user's data storage, software and computation over a network, for example. Such computing capability relies on sharing of resources to achieve coherence and economies of scale similar to a utility (like the electricity grid) over a network (typically the Internet).
One aspect of services to support cloud computing relates to Infrastructure as a Service models (IaaS), where cloud service providers offer computers, as physical or more often as virtual machines, and other computing resources. The virtual machines can be run as guests by a hypervisor service, for example. Management of pools of hypervisors by the cloud operational support system leads to the ability to scale to support a large number of virtual machines. Other resources in IaaS clouds include images in a virtual machine image library, raw (block) and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles.